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Author Topic:   Climate Change Denier comes in from the cold: SCIENCE!!!
Percy
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Posts: 17875
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.3


Message 511 of 515 (841743)
10-21-2018 8:51 AM
Reply to: Message 510 by Stile
10-19-2018 9:47 AM


Re: A Sort Of Climate Change Related Question
Excellent and well explained. Thank you.

Stile writes:

However, if you've ever stood up a shelving unit at this point, you know it's very weak against lateral-movement still. If you push it from one side, the two side-ends (the "studs") push over together and the "blocking" shelves barely do anything to stop this motion. Of course... the shelves aren't nailed into the studs where the blocking would be... but this isn't adding a lot of structure... only the connection point of the single-nails-per-blocking-per-stud. It's still relative-ly weak against lateral movement.

However, there's always that super-flimsy back piece you put on those shelves. Put that on... and the entire shelf suddenly becomes super-rigid.

Doh! Yes, of course, I see now. Blocking in the shape of an 'X' would be far more effective than a horizontal block, but only structurally. It would be useless for providing a connection point where two pieces of plywood join.

This image was helpful:

So the hinge point they were actually talking about is near where that arrow is pointing at the junction between the truss and the side wall. I had wrongly assumed that the hinge point they were talking about was on the side of the building away from the arrow, again where the truss meets the side wall.

On which side of the gable would one install hurricane clips, the end where the arrow is, or on the sides? If the answer is both then how would windstorm plywood eliminate the need for hurricane clips on the side. Or if you don't need hurricane clips on the side then why not? Isn't lift generated here, too? In fact, isn't the danger of rollover from the sides, not the gable ends?

Your answer about hardware makes sense.

Thanks for the effort it took to explain all this.

--Percy


This message is a reply to:
 Message 510 by Stile, posted 10-19-2018 9:47 AM Stile has responded

Replies to this message:
 Message 512 by Stile, posted 10-22-2018 9:28 AM Percy has acknowledged this reply

    
Stile
Member
Posts: 3257
From: Ontario, Canada
Joined: 12-02-2004
Member Rating: 2.5


Message 512 of 515 (841807)
10-22-2018 9:28 AM
Reply to: Message 511 by Percy
10-21-2018 8:51 AM


Re: A Sort Of Climate Change Related Question
Percy writes:

Doh! Yes, of course, I see now. Blocking in the shape of an 'X' would be far more effective than a horizontal block, but only structurally. It would be useless for providing a connection point where two pieces of plywood join.

Absolutely.

On which side of the gable would one install hurricane clips, the end where the arrow is, or on the sides?

I'm not really sure.
My guess is either "on the sides" or "everywhere."

If the answer is both then how would windstorm plywood eliminate the need for hurricane clips on the side. Or if you don't need hurricane clips on the side then why not? Isn't lift generated here, too? In fact, isn't the danger of rollover from the sides, not the gable ends?

I think there are two different problems.

The hinge point at the gable-end-frame is one problem. I think we understand that one now, and how windstorm sheathing prevents it.

The other problem is the whole lift-issue and danger of rollover.
And I think you're right - these are a problem more on the sides, not the gable-end faces.

Therefore, the wind would have to change direction from those pictures and come from one of the sides in order to cause this second issue.

In my previous post - the section talking about the "butt-cut" and using windstorm sheathing from the bottom-of-the-wall to meet up with the bottom-of-the-top-chord-of-the-roof (covering the "butt-cut") is about protecting these sides and helping to greatly reduce lift along the sides. The windstorm sheathing connects the wall section to the roof section better (apparently) than hurricane clips.

I don't really know what a hurricane clip is... but I'm guessing some sort of single-point connector spaced out every 12" or so along the roof-wall connection line.

With no windstorm sheathing (and either a narrow piece of plywood covering the butt-cut or nothing covering the butt-cut at all...) these hurricane clips would be the only thing holding the roof onto the wall section. Perhaps there are some nails... but these would be vertical (from the roof down into the wall) - these vertical nails wouldn't do much in stopping the vertical lift from winds.

With the windstorm sheathing, we now continue the "flimsy-Ikea-backpiece-greatly-increasing-structural-stability" idea up from the wall section and onto the butt-cut area of the roof section. The horizontal nails holding the windstorm sheathing to the roof butt-cut section would be a great deterrent against vertical lift. As well, there would be many more nails in each windstorm-sheathing piece then there would be hurricane clips (I would guess).

Thanks for the effort it took to explain all this.

No problem. It was interesting for me too.


This message is a reply to:
 Message 511 by Percy, posted 10-21-2018 8:51 AM Percy has acknowledged this reply

    
Percy
Member
Posts: 17875
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.3


Message 513 of 515 (841997)
10-25-2018 7:49 AM


Climate Change Comes to Hawaii
It was recently discovered that several weeks ago Hurricane Walaka wiped a tiny Hawaiian island off the map. East Island was in the extreme northwest of the Hawaiian island chain and is thought to have only been a couple thousand years old. Scientists knew the island was vulnerable to climate change but expected it would endure another decade or two. Here's a before/after image of the former island:

In related news, a category 5 typhoon just hit the Northern Mariana Islands (it's a US territory about 3/4 of the way toward the Philippines from the Hawaiian islands, not too far from Guam). The government there is calling it the worst storm they've ever experienced:

--Percy


Replies to this message:
 Message 514 by RAZD, posted 10-25-2018 12:00 PM Percy has acknowledged this reply

    
RAZD
Member
Posts: 19666
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 2.9


Message 514 of 515 (842009)
10-25-2018 12:00 PM
Reply to: Message 513 by Percy
10-25-2018 7:49 AM


Re: Climate Change Comes to Hawaii
try link instead
https://e3.365dm.com/...52/skynews-hawaii-island_4463733.jpg

Enjoy

Edited by RAZD, : ??

Edited by RAZD, : .


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This message is a reply to:
 Message 513 by Percy, posted 10-25-2018 7:49 AM Percy has acknowledged this reply

  
Percy
Member
Posts: 17875
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.3


(1)
Message 515 of 515 (842198)
10-27-2018 4:34 PM


Northern Mariana Islands Before/After Photos
This Washington Post article has before/after aerial photos of the Northern Mariana Islands: Satellite images of destruction by Super Typhoon Yutu in the Northern Mariana Islands

--Percy

Edited by Percy, : No reason given.


    
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